1. Field of the Invention
The present invention relates generally to a computer implemented method, data processing system, and computer program product for collecting server statistics. More specifically, the present invention relates to sampling power consumption statistics during typical high-load periods such that a power limit or power cap is discovered that a server, as configured, does not surpass.
2. Description of the Related Art
Modern data centers may be placed in dense urban areas. Some may be placed in high-rise buildings. Architecture and geography may limit the power available at a data center. These constraints may limit the number of servers that can be placed in the data center.
In the past, system administrators to such data centers would make educated guesses as to the maximum power consumption for each server. For each server, a system administrator would select a capped power usage, or power cap, that applies to a given server. A power management module (PMM) can throttle a server that approaches or exceeds the applicable power cap for that server. A PMM apportions a net power limit among the devices of a target system. Accordingly, a PMM may be a data processing system that communicates with components within a rack or other electronic enclosure that monitors power use, and instructs each device to moderate consumption as needed.
In designing and planning growth of a data center, a system administrator allocates to each server, power on a worst-case scenario basis. In the system administrator's mind, the combined power consumption of all servers during the worst-case scenario must be below the rated capacity of a power line that feeds the data center. Otherwise, over-current circuit protection may be triggered, such as, for example, a circuit breaker.
Control of each server's maximum power can be provided by an energy manager application that may control power to each server through a power management module (PMM) coupled to each to a server. The energy manager and/or the PMM provides a graphical user interface for power management. Thus, a system administrator is permitted a range of power cap limitations between a minimum and a maximum limit on a scale of watts within a graphical user interface. A power cap is a limit set by a user or determined by a data processing system to apply to a server. The power cap may be an educated guess or a calculation concerning a likely expected maximum power that a server may require. The power cap can be used as a planning tool to determine how much of a data center's power budget is already allocated to servers in the data center. The power cap can be used as a threshold for a server to self-determine dangerous over-use of power, and accordingly throttle back power consumption when the threshold is approached or surpassed.
The lower limit and upper limit are called, pcapmin and pcapmax, respectively. Setting a power cap close to the pcapmax, can provide the system administrator a high assurance that the power will not be throttled back on a server, but at the expense of allocating a larger fraction of the power of the data center to this particular server. Accordingly, a system administrator may be unaware that a particular server, custom configured to the customer's needs, is maxing out at a level well below the power cap. Thus, by over-engineering power to this particular server, the system administrator may be overlooking a surplus of power allocation that could be allocated to a new server.
The system administrator, absent knowledge of surpluses in power allocation versus actual power drawn, cannot place as many servers in a data center as might be available if more realistic power caps were placed on each server.